The purpose of this proposal is to develop mathematical tools for predicting lead burdens in human populations. Multicompartment kinetic models previously developed for lead concentrations in blood plasma and erthrocyte components will be extended to include effects of blood lead levels on the inhibition of ALAD formation, EP, and ZPP. Preliminary analyses suggest that nonlinear kinetic mechanisms must be assumed for the exchange of lead between plasma and erythrocytes. The models will be tested against sets of data. Relationships among concentrations of Pb-B, ALAD, and plasma lead will be derived from the kinetic models developed above. Long-term kinetic models will be used to estimate lead burdens in teeth and in cortical and trabecular bone of exposed populations. Statistical methods for testing competing hypothesis about nonlinear kinetic models will be compared using computer simulation techniques.